Distributor having a snap-fitted rotor



March 10, 1964 D. w. O'BRIEN 3,124,566

- DISTRIBUTOR HAVING A SNAP-FITTED ROTOR Filed May 26, 1961 1N VENTOR.

1913 ATTOR/Vf) United States Patent 3,124,666 DISTRIBU'IDR HAVING A SNAP-FIITED RUIQR Donaid W. QBrien, Anderson, Ind, assignor to General Motors Corporation, Detroit, Mich, a corporation of Deiaware Filed May 26, 1961, Ser. No. 113,020 1 Claim. (6!. 20019) This invention relates to distributors for controlling the ignition timing of an internal combustion engine and more particularly to the distributor rotor.

One of the objects of this invention is to provide a distributor rotor that may be snap fitted to a part that is driven by the distributor shaft.

Another object of this invention is to provide a distributor rotor that is formed of plastic material and which has projecting teeth that are adapted to be passed through openings in a distributor weight base and then snap outwardly to engage one side of the weight base.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein preferred embodiments of the present invention are clearly shown.

In the drawings:

FIGURE 1 is a side elevation with parts broken away of a distributor having a rotor made in accordance with this invention.

FIGURE 2 is an enlarged line 2-2 of FIGURE 1.

FIGURE 3 is -a perspective view illustrating the rotor and weight base of the distributor shown in FIGURE 1.

FIGURE 4 is a view similar to FIGURE 2 showing a wedge means for spreading the teeth of the rotor.

Referring now to the drawings and more particularly to FIGURE 1, a distributor is illustrated which has a metal base that carries a distributor cap 12. The distributor cap 12 has a center electrode 14 and a plurality of circumferentially spaced electrodes '16. The electrode 14 and electrode 16 cooperate in the usual manner with a rotor spring assembly generally designated by reference numeral 18. This rotor spring assembly 18 is carried by a rotor which is generally designated by reference numeral 20. The rotor 20 is formed of a plastic material such as polypropylene and is carried by a weight base designated by reference numeral 22.

The weight base 22 is connected with the cam of the distributor for example, in a manner illustrated in the patent to Julian, et al., 2,945,923, and is driven by the distributor shaft. The weight base 22 of the distributor shown in FIGURE 1 may also carry the centrifugal weight mechanism in a manner illustrated in the above noted Julian, et al. patent. In other respects, the distributor of FIGURE 1 may be identical with that shown in the above-noted Julian patent in that a breaker plate is provided which is shifted by the conventional vacuum unit.

The distributor rotor 20 actually has what may be termed a snap fit with the weight base 22. To this end, the lower side of the rotor 26 is provided with integral projecting teeth 24 and 26 which are slipped through openings 28 formed in the weight base 22 and which then snap outwardly to engage the underside 30 of the weight base. It is seen that there are openings 32 which pass through the rotor 20*. The teeth 26 and 24 are separated by a continuation of the opening 32 as is clearly apparent from FIGURES 2 and 3. The teeth 24 and 26 have shoulders 24a and 26a which engage the underside of the weight base 22 once the teeth 24 and 26 are pushed through the openings 28 and after the teeth snap outwardly to a position where the shoulders partially engage the underside 30 of the weight base 22. The teeth 24 and 26 also have slanted surfaces 24b and sectional view taken along 3,124,666 Patented Mar. 10, 1964 265 which permit easy insertion of the teeth into the openings 28. It will be apparent from FIGURE 1 that there are two pairs of teeth 24 and 26 which pass through the openings 28 formed in the weight base 22.

In addition to the snaps or teeth 24 and 26, the rotor 22 is provided with projecting lugs 34 and 36 which pass through openings 38 and -40 formed in the weight base 22. The lug 34 preferably has a square configuration whereas the lug 36 preferably has a circular configuration. The openings 38 and 40 of course have complementary shaped openings.

When it is desired to fit the rotor 20 of this invention to the weight base 22, the teeth and lugs are lined up with their respective openings and the teeth and lugs are then pushed into their respective openings in the weight base 22. As the lugs 24 land 26 pass through the openings 28, they are moved toward one another but once they clear the bottom surface of the weight base 22, they snap outwardly into tight engagement with the underside 30 of the weight base. The lugs 24 and 26 thus serve to prevent the rotor 20 from moving axially relative to the weight base 22 whereas the lugs 34 and 36 are intended to prevent relative rotative movement between the weight base 22 and the rotor 20.

Referring now more particularly to FIGURE 4, a modified arrangement is illustrated wherein a wedge is provided for forcefully spreading the teeth 24 and 26 once they have been snapped through the opening 28 in the weight base 22. This wedge takes the form of a screw 42 which is threaded into the opening 32 formed in the rotor 20 and which passes downwardly into the space 3-3 located between the teeth 24 and "26 to insure that the teeth tightly grasp the underside of the weight base 22. It will of course be appreciated that other devices than screws might be used as a wedge for wedging the teeth 24 and 26 apart.

While the embodiments of the present invention as herein disclosed, constitute a preferred form, it is to be understood that other forms might be adopted.

What is claimed is as follows:

In combination, a distributor having a distributor cap, said distributor cap having a plurality of circumferentially spaced electrodes, a part rotatable with respect to said distributor cap having first and second pairs of openings, a rotor formed as a one-piece plastic part carried by said distributor cap having an electrode which cooperates with said circumferentially spaced electrodes of said distributor cap, said rotor having a first pair of integral projections fitting within said first pair of openings in said rotatable part and having a second pair of integral teeth passing respectively through said second pair of openings in said rotatable part, a portion of each of said teeth engaging an underside of said rotatable part to prevent axial separation of said rotor from said rotatable part, said projections and teeth forming a means for driving said rotor from said rotatable part, and wedge means for forcing said teeth outwardly and retaining said portions of said teeth in tight engagement with the underside of said rotatable part, said rotor being snap-fitted to said rotatable part prior to insertion of said wedge means that force said teeth outwardly.

References Cited in the file of this patent UNITED STATES PATENTS 2,769,047 Hartzell et al. Oct. 30, 1956 2,788,047 Rapata Apr. 9, 1957 2,788,401 McCarty Apr. 9, 1957 2,828,393 Wingard Mar. 25, 1958 2,945,923 Julian et al. July 19, 1960 FOREIGN PATENTS 707,819 Great Britain Apr. 21, 1954 

